Recent advances in basic science Interleukin-22 orchestrates a pathological Gut: first published as 10.1136/gutjnl-2019-318483 on 2 December 2019. Downloaded from endoplasmic reticulum stress response transcriptional programme in colonic epithelial cells Nick Powell ,1,2,3 Eirini Pantazi,1 Polychronis Pavlidis ,1 Anastasia Tsakmaki,4 Katherine Li,5 Feifei Yang,5 Aimee Parker,6 Carmen Pin,6 Domenico Cozzetto,2,7 Danielle Minns,1 Emilie Stolarczyk,1 Svetlana Saveljeva,8 Rami Mohamed,1 Paul Lavender,1 Behdad Afzali,1 Jonathan Digby- Bell,1 ,Tsui Tjir- Li 1 Arthur Kaser,8 Joshua Friedman ,5 Thomas T MacDonald,9 Gavin A Bewick ,4 Graham M Lord1,2,10 ► Additional material is ABStract of IBD remains elusive, and the role of individual published online only. To view Objective The functional role of interleukin-22 (IL22) cytokines and immune pathways can be difficult please visit the journal online to deconvolute. Simultaneous mobilisation of anti- (http:// dx. doi. org/ 10. 1136/ in chronic inflammation is controversial, and mechanistic gutjnl- 2019- 318483). insights into how it regulates target tissue are lacking. inflammatory and tissue restitution factors adds yet In this study, we evaluated the functional role of IL22 in further complexity to the picture. Interleukin-22 For numbered affiliations see (IL22) is a highly controversial cytokine. Currently, end of article. chronic colitis and probed mechanisms of IL22-mediated regulation of colonic epithelial cells. the prevailing view is that IL22 promotes gastroin- + Correspondence to Design To investigate the functional role of IL22 in testinal health by supporting LGR5 epithelial stem 2 Dr Nick Powell, Division of chronic colitis and how it regulates colonic epithelial cell regeneration/proliferation. This protective Digestive Diseases, Faculty of cells, we employed a three- dimentional mini- gut role is most obviously observed in animal models Medicine, Imperial College epithelial organoid system, in vivo disease models and of intestinal epithelial injury resulting from acute, London, London W2 1NY, UK; self- limiting insults. In acute colonic infections, npowell@ ic. ac. uk and Professor transcriptomic datasets in human IBD. Graham M Lord, School of Results As well as inducing transcriptional modules such as Citrobacter rodentium, where rapid repair Immunology and Microbial implicated in antimicrobial responses, IL22 also of colonic epithelial cells is required, IL22 plays a Sciences, King’s College London, coordinated an endoplasmic reticulum (ER) stress protective role.3 4 Likewise, IL22 facilitates epithe- London, SE1 9RT; response transcriptional programme in colonic epithelial lial restitution after induction of acute injury after graham. lord@ kcl. ac. uk cells. In the colon of patients with active colonic Crohn’s short- term exposure to the detergent DSS, which http://gut.bmj.com/ Received 10 February 2019 disease (CD), there was enrichment of IL22-responsive results in abrupt tissue injury that rapidly resolves Revised 15 October 2019 transcriptional modules and ER stress response modules. shortly after removal of the chemical insult.5 6 Accepted 31 October 2019 Strikingly, in an IL22- dependent model of chronic colitis, Administration of the chemotherapy agent metho- Published Online First trexate also induces a self-resolving mucositis char- 2 December 2019 targeting IL22 alleviated colonic epithelial ER stress and attenuated colitis. Pharmacological modulation of the acterised by acute small intestinal epithelial damage, ER stress response similarly impacted the severity of in which IL22 plays an important restorative role.7 colitis. In patients with colonic CD, antibody blockade of Importantly, in these examples, the primary insult is on September 25, 2021 by guest. Protected copyright. IL12p40, which simultaneously blocks IL12 and IL23, the epithelial disruption, where it seems IL22 performs key upstream regulator of IL22 production, alleviated the an important restorative role, driving epithelial colonic epithelial ER stress response. proliferation and restitution. Together these data Conclusions Our data challenge perceptions of IL22 as have been interpreted as indicating that IL22 could a predominantly beneficial cytokine in IBD and provide be clinically useful to promote epithelial repair in novel insights into the molecular mechanisms of IL22- IBD and has culminated in a clinical trial evaluating mediated pathogenicity in chronic colitis. Targeting IL22- the role of recombinant IL22 therapy in patients regulated pathways and alleviating colonic epithelial ER with active IBD. stress may represent promising therapeutic strategies in However, an alternative view of IL22 is emerging patients with colitis. to challenge this dogma, especially in the context Trial registration number NCT02749630. of chronic inflammation, rather than acute, self- limiting mucosal injury. IBD is not an acute inflam- matory disease, and in the majority of patients nor is it likely to be caused by a primary epithelial defect. INTRODUCTION IBD has been a major beneficiary of the genome © Author(s) (or their Inflammatory bowel disease (IBD), comprising wide association studies (GWAS) revolution, and employer(s)) 2020. Re- use ulcerative colitis (UC) and Crohn’s disease (CD), while disease risk conferring polymorphisms at permitted under CC BY. is a paradigmatic immune-mediated inflammatory epithelial loci are recognised, the majority of them Published by BMJ. disease (IMID). IBD is characterised by excessive localise at immune genes. Some preclinical models To cite: Powell N, Pantazi E, accumulation of immune cells in the gut and induc- of IBD indicate that IL22 may actually contribute Pavlidis P, et al. Gut tion of complex inflammatory networks.1 Similar to disease.8–11 Moreover, blockade of IL23, the key 2020;69:578–590. to the situation for other IMIDs, the precise cause upstream cytokine responsible for triggering IL22 578 Powell N, et al. Gut 2020;69:578–590. doi:10.1136/gutjnl-2019-318483 Recent advances in basic science production, looks to be very promising in early phase clinical inducer of a pathological ER stress response.16 Tunicamycin signifi- studies in IBD.12 13 Indeed, high serum levels of IL22 predict cantly modulated the expression of 217 genes in colonoids (online Gut: first published as 10.1136/gutjnl-2019-318483 on 2 December 2019. Downloaded from response to anti- IL23 treatment.13 Consequently, additional supplementary table 2), and enrichment analysis for functional insights into the role of IL22 in chronic colitis are urgently annotation groups demonstrated significant association with needed to inform therapeutic strategy, especially now that clin- cellular processes associated with ER stress, including ‘response ical trials evaluating the efficacy of recombinant IL22 adminis- to unfolded protein’ and ‘response to ER stress’ (online supple- tration to patients with active IBD are starting to be pursued. mentary figure 2). Gene Set Enrichment Analysis17 confirmed Accordingly, there is a pressing need for new insights into significant enrichment of the colonic epithelial compartment- the role of IL22 in chronic inflammation. Importantly, the IL22 specific ER stress response transcriptional module in IL22 treated receptor is exclusively expressed by epithelial cells in the gut, and colonoids (figure 1B). These data were corroborated by real time in IBD, there is an especially compelling case to probe interac- PCR, confirming that IL22 induced transcription of core ER stress tions between IL22 and the colonic epithelium, since the colon is response transcripts in a time and dose dependent manner (online exclusively affected in UC and affects most patients with CD.1 In supplementary figure 3). We validated these findings in an indepen- this study, we have exploited colonic epithelial organoids, in vivo dent, published dataset of genome- wide transcriptional changes in disease models and tissue transcriptomics in a large datasets of CD colonic epithelial cells generated using a different gene expression patients with active colitis to probe IL22- colonic epithelial inter- platform (RNA sequencing).18 In agreement with our data, IL22 actions and provide mechanistic insights into this critical dialogue. induced an ER stress response transcriptional programme in WT colonoids, but not in Il22ra1−/− colonoids, additionally confirming METHODS that this pathway is dependent on signalling through the conven- tional IL22 receptor (figure 1C). Comparable findings were Experimental methods, including in vivo treatment, cell isola- observed at pathway level, with significant enrichment of tran- tion protocols, organoid cultures, gene expression profiling, scripts annotated to Gene Ontology (GO) terms, such as ‘response immunoblotting, immunohistochemistry, fluorescence activated to ER stress’ and ‘ER stress overload response’ (figure 1D). cell sorting (FACs), details of the UNITI trial programme and We also observed that IL22 synergistically augmented statistical methods are shown in online supplementary methods. tunicamycin-induced transcription of core ER stress genes in our microarray analysis (figure 1E and online supplementary table 3), RESULTS which was corroborated by real time PCR (online supplementary IL22 regulates an endoplasmic reticulum (ER) stress response figure 4), indicating that IL22 might also potentiate the ER stress transcriptional module in colonic epithelial cells, which is response driven by other mediators. We reasoned that this might augmented by